Inebilizumab Benefit Consistent Across MG Subgroups: Richard Nowak, MD

The randomized controlled period (RCP) in the phase 3 MINT trial of inebilizumab for myasthenia gravis (MG) wasn't reported over the same length of time for every subgroup, and Richard Nowak, MD, MS, associate professor of neurology at Yale School of Medicine and global principal investigator of the MINT trial, wants to make sure that discrepancy isn't misread as a design flaw.

Why the Follow-Up Periods Differ

The primary study's RCP ran 26 weeks for the combined study population, which includes both acetylcholine receptor (AChR) and muscle-specific kinase (MuSK) antibody-positive patients. That period was pre-specified to run longer, 52 weeks, for the AChR subpopulation specifically, while the MuSK subpopulation was analyzed at 26 weeks along with the combined group. Both groups then had the option to enroll in an open-label extension running approximately 3 years, which is still ongoing.

"It's not that it was only for 52 weeks for the AChR, but rather that we have 52 weeks of data that we can analyze and present in our recent publication," Nowak said.

Efficacy Held Across Every Subgroup

Across every population analyzed, the topline result held steady. In the 26-week combined population, the probability of MG exacerbation was reduced with inebilizumab compared with placebo, a pattern repeated separately in both the AChR and MuSK subpopulations. Looking at the AChR group's fuller 52-week window, that same reduction in exacerbation probability persisted. Rescue therapy use followed the identical pattern: reduced with inebilizumab versus placebo in the 26-week combined population, in both antibody subgroups individually, and again in the AChR group's 52-week data. Nowak pointed to the study's Kaplan-Meier curves, published in JAMA Neurology, as the clearest way to see the full picture across combined and antibody-specific populations.

"The Kaplan-Meier curves very nicely summarize these data in terms of probability of exacerbation, probability of rescue therapy use in the treatment arm for the combined and the antibody subpopulations as well," Nowak concluded.